将徽标动态添加到 R 绘图

Question

library(dagitty)
library(ggplot2)
library(ggdag)

get_jpg <- function(filename) {
  grid::rasterGrob(jpeg::readJPEG(filename), interpolate = TRUE)
    }
logo <- get_jpg("logo.jpg")

ex.1 <- dagitty("dag { 

X <- A -> B <- C -> Y
X <- B -> Y
X -> W -> Y
S-> T -> C
}")

exposures(ex.1) <- 'X'
outcomes(ex.1) <- 'Y'

tidy.1 <- ex.1 %>% 
  tidy_dagitty() %>%
  mutate(label = str_to_upper(name)) 


ggdag(tidy.1 , text = FALSE, use_labels = "label") + theme_dag() +
  theme_light() +
  annotation_custom(logo, xmin = 6.5, xmax = 8.5, ymin = -5, ymax = -8.5) +
  coord_cartesian(clip = "off") +
  theme(plot.margin = unit(c(1, 1, 3, 1), "lines"))

我有这段代码可以在我的情节中放置一张 JPG 图像。我了解 xmin、xmax、ymin ymax 坐标未对齐。有没有办法可以在图表的右下角显示图像（类似于此处显示的图像：https://www.markhw.com/blog/logos）？如果可能，我想在不指定坐标的情况下动态地执行此操作，因为我不确定 ggdag 如何为因果图绘制 x 和 y 坐标。

谢谢！

Answer 1

实现所需结果的一种方法是通过rasterGrob 而不是annotation_cutom 设置坐标来定位徽标。利用您在下面我的代码中链接的帖子中的示例代码，我将 R 徽标放在右下角。从我添加的两个示例中可以看出，这与数据范围无关，并且将始终将徽标放在同一位置：

library(tidyverse)

download.file("https://www.r-project.org/logo/Rlogo.png", "logo.png")

get_png <- function(filename, x = unit(0.5, "npc"), y= unit(0.5, "npc"), 
                    width = NULL, height = NULL, gp = grid::gpar()) {
  grid::rasterGrob(png::readPNG(filename), interpolate = TRUE,
                   x = x, y = y, width = width, height = height, gp = gp)
}

species <- starwars %>% 
    count(species) %>% 
    filter(!is.na(species) & n > 1) %>% 
    arrange(-n) %>% 
    mutate(species = factor(species, species))

width = 3
l <- get_png("logo.png", 
             x = unit(1, "npc") - unit(width / 2, "lines"), 
             y = unit(-width, "lines"), 
             width = unit(width, "lines"))

p_fun <- function(x, width = 3) {
  ggplot(x, aes(x = species, y = n)) +
    geom_bar(stat = "identity") +
    coord_cartesian(clip = "off") +
    theme_light() +
    theme(plot.margin = unit(c(1, 1, width, 1), "lines"))
}

p_fun(species) +
  annotation_custom(l)

p_fun(filter(species, n > 2)) +
  annotation_custom(l)